Nesting habits of fish

When most fish reproduce, they excrete their eggs from the body. The previous generation has already fulfilled its responsibilities to the offspring. As for whether they can survive and grow and develop safely, they can only let nature take its own course. Often this method of reproduction only relies on laying a large number of eggs, hundreds of thousands, millions, or even hundreds of millions of eggs, to ensure that some of the eggs can be fertilized, hatched, and developed until they grow up, so that the population can continue to reproduce. But for some species, usually a female fish can only lay a few or dozens of eggs in one reproductive season. In order to ensure the continuation of offspring, these fish often have a certain degree of protection from both parents or one of them. The habit of protecting young is reflected in the habit of building nests, guarding the hatching of fish eggs, and caring for young fish.

The nest is used to store fertilized eggs, and its structure can range from a simple cave (or river bottom) to an exquisite and complex facility to protect the development of fertilized eggs until they hatch into larvae. Some species guard the larvae until they can feed freely and have certain swimming abilities before allowing them to live on their own.

1. Stickleback fish and others use water plants to build nests

During the reproductive period of stickleback, the male first chooses a suitable location to lay eggs in the shallow water area of the stream. The male stickleback picks up the thin stems of the cabbage with its mouth, and secretes a transparent mucus from its own kidneys. This secretion is excreted through the ureter and solidifies when it encounters water or air, thereby absorbing the thin stems of the cabbage. The stems are sticky and woven into fish nests suitable for laying eggs. Mr. Lorte observed the nesting process of sticklebacks on Vancouver Island, and he made this record: "During the work, the male swam toward the nest and splashed water from time to time, seemingly testing the strength of the nest; often Use your body to rub the small bed, use the mucus on your sides to mix them, so that it becomes the cement slurry for the water grass bricks. Secondly, use your kiss to reach into the sand at the bottom of the water, take a mouth full of sand, and scatter it in this Basically. Work in this way repeatedly until the crib is pressed strong and stable.

In order to test the solidity of all the materials of this foundation, it is often poured with water. The completed nest is a hollow and slightly round thing, which is completely attached to a basic surface fixed on the water plants. The entire nest is sealed firmly with the mucus of the body. The plaster-like tissue inside the nest needs to be made as smooth as possible. The little builder tosses and turns in the nest and coats the inner wall with mucus, as if the inner wall has been coated with a layer of solid fake paint. "It took several days for the male fish to build a transparent nest that is spherical in shape, with an opening at the top and no roof. Looking down, you can see the eggs laid in it. The inner diameter is 3 cm, the outer diameter is 4 cm, and the height is about 2.5 cm.

After the male fish builds the nest, he goes out to find a partner. After the female is selected, the male fish has to perform a complex set of courtship moves and finally introduce the female into the nest. The male fish looked very happy, swimming around the female fish, and invited her to enter the nest from the side of the nest. The male fish keeps touching the female fish's back with his kiss. At this time, if the female fish hesitates to enter the nest, the male fish will use his spines to prick her. After the female fish enters, she lays a few eggs and then exits from the opposite side. When the female fish is in the nest, the male fish swims very excitedly, knocking and wiping the nest with his kiss from time to time. After the female fish runs away, the male fish immediately enters the nest, injects semen on the eggs, and then swims out of the nest. . The next day, the male fish pursues another female fish in the same way as last time. This goes through several times until the eggs in the nest are full.

Wrasses and snakeheads also use aquatic plants to build nests. Wrasses use seaweed to build their nests on rocks at a depth of 0.5-2.5 meters underwater. They are shaped like a bird's nest with pits in the middle. Usually male and female fish jointly participate in nest building. The African lungfish digs a hole in the mud of the swamp and surrounds it with water plants. Before the snakehead lays eggs, the male and female broodstock jointly pick up aquatic plants or plant fragments to build a fish nest. Nesting sites are mostly chosen in ponds and rivers with dense aquatic plants, or on shallow water beaches with reeds. The nest is slightly circular, and the size depends on the individual parent fish. Generally, for a parent fish of about 500 grams, the diameter of the nest will be About 40-50 cm.

2. Yellow catfish and other fish dig mud to build nests

Some fish dig mud and build nests on the muddy bottom, such as yellow catfish, barbel fish, tilapia, etc. The male yellow catfish has the habit of making a nest. During the reproductive period, the male fish swims to the silt clay with dense aquatic plants along the coast (water depth 8-40 cm), and uses its pectoral fin spines to rotate intermittently on the mud bottom to dig into a nest. The small mud pits are fish nests. Some of them are together, and there are also dozens of them in groups, not far apart to form cave groups. Some fish build nests on the bottom of gravel, such as salmon, lamprey, and Qinghai Lake naked carp. After salmon arrives at the spawning ground, it chooses a place with a quiet environment, clear water quality, turbulent water flow, moderate water temperature, and a gravel bottom. The male fish beats the gravel with its tail fin and uses the impact of the water flow to form a hole with a diameter of 1 meter and a depth of about 1 meter. A 20 cm pit, this kind of nest is called a "lying nest".

The female fish lays eggs in the nest and buries the eggs by repeatedly moving the gravel with her tail fin. The spawning site of lampreys is similar to that of salmon. After the male arrives at the spawning site first, he first selects a site to start building a nest, and the female fish arrives later and works together. They use their sucker-shaped mouth to suck up small stones, use dragging and shaking methods to loosen them, and drag them to the downstream of the nest to build a push, forming an oval or round nest with a diameter of 50-80 cm on the river bottom. The pits are their ovaries. During the reproductive season of Qinghai Lake naked carp, the male uses his anal and tail fins to sweep the gravel on the river bottom into shallow pits, and most of the eggs laid are concentrated in the pits.

3. Goby fish can build hidden nests

There is a kind of small goby fish that can build exquisite hidden nests. The male fish first turns the empty shell over so that the concave side faces down, then gets in and uses its tail fin to scrape the sand away to form a small chamber, and finally digs a channel to communicate with the outside world. Snakeheads use submerged shelters such as clams, tiles or broken earthen jars as nests for laying eggs.

The nest of the swim bladder bass is also very special. It chooses the space between the rock bottom and the bottom gravel in the water as a place to lay eggs. The distance between this space is about 15-25 mm, which is exactly the same as the height of the fish body when the dorsal fin is vertical. The male fish first uses the end of the fleshy bulbous dorsal fin spine to clear the bottom of the rock so that the eggs can adhere. Many fascinating fish (such as betta fish) can build the most extraordinary nests. The male fish chooses a calm and sheltered place on the water surface. He blows air from his mouth and spits out mucus to form small bubbles. Countless small bubbles stick together to form a nest. A floating nest with a raised or slightly flat surface.

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